Structures that can be collapsed during transit and deployed upon reaching their destination have been widely used, particularly in situations in which cargo space is limited or otherwise at a premium. Advantageously, collapsible structures may be stowed compactly in a vehicle while not in use, and then deployed to a desired configuration to perform a given application. Although the space-saving characteristics of collapsible structures benefit many applications, space applications in particular stand to benefit to a high degree due to the limited amount of cargo space onboard a spacecraft and the high cost of space travel.
Large antennas are oftentimes deployed to orbit the earth and to perform various tasks, such as collecting radar images, tracking ground-based and air-based targets, and providing high-bandwidth communications. Such antennas usually require relatively large apertures, as well as heavy electronics packaging and support structures. In addition, most antennas cannot be retracted and collapsed once fully deployed. As a result, the antennas cannot be collapsed into a spacecraft and returned to Earth for future applications. Although lightweight electronics packaging and support structures may reduce total mass, the antennas still generally require large apertures such that the overall antenna structure remains quite large. Since the antennas are generally transported into space onboard a spacecraft, an important design factor is the ability to efficiently package a large antenna structure inside of the launch vehicle payload volume, while still permitting the antenna to be deployed once in space.
Several approaches currently are used to address the transportation of large deployable antenna systems on a spacecraft. One method utilizes discrete folding panels that are capable of folding into a relatively small size, but that deploy into the larger antenna structure when in orbit. Under this approach, however, the folded panels produce a dense stowed package that leaves little room for storing other objects. Another method commonly used to stow large deployable space structures that are formed of a number of tubes is to fold and/or nest the tubes. The tubes can then be unnested and unfolded to produce a truss structure of a desired size, shape, and stiffness. Under this approach, however, the size of the deployed structure and the complexity of the electronics packaging being supported by the structure requires a highly complex system of hinges, cables, and drive components. As a result, the structure is generally relatively unreliable and is disadvantageously heavy.
It would therefore be desirable to provide a deployable antenna structure that not only is relatively light, but can also be stowed and deployed in an effective manner. In order to facilitate the deployment of the antenna, particularly in space applications, it would be desirable to provide a means for deploying and/or retracting the structure without the use of drive components or other motors. Finally, it would be desirable to provide an antenna structure that could be retracted into a vehicle to be used again for future applications.
Accordingly, while a variety of collapsible structures, including antennas, have been developed, most of the structures remain disadvantageously heavy and oftentimes consume a substantial portion of the cargo space. In addition, a number of the collapsible structures require a complex system of hinges, cables and drive components for their deployment. Thus, a collapsible structure, such as an antenna, that can be stowed in a compact manner, can be self-deployed and need not include a mechanically complex deployment system is desirable, particularly for space applications.